"Greeks are heavy coffee drinkers," adds Kantaroglou. "We also like to socialize in cafes unlike, say, the Italians with their quick drink-and-go espresso shots."

Once finished, we turn over the cups and let the residue run down inside; there are still professional coffee readers who will predict your future from the resulting pattern.

None are present so early in the morning, so we put our fate in Kantaroglou's hands and head out.

We're on the trail of some of the best street food in Athens -- a culinary scene that's changed rapidly in recent years as Greek economic woes and the recent European migrant crisis have had an unexpectedly delicious impact on the city's eating habits.

Originating from Thessaloniki in northern Greece, the bougatsa is substantial yet light. Its crisp filo complements a creamy filling, while a cinnamon dusting binds the flavors together.

Thessaloniki also gives us koulouri: a baked dough ring with sesame that's been compared to German pretzels or Jewish bagels.

This is the ultimate Greek street food, costing just a dollar. It's typically on sale from early morning as vendors try to cash in on the hangover munchies of late-night revelers heading home.

It may be humble, but it's causing a small food revolution in Athens.

In March 2016, the new Oven Sesame franchise (Oven Sesame, Aiolou 17, Athens; +30 21 0323 0038) started experimenting with the traditional round shape and with fillings that range from cheeses and salads to meats and even ice cream.

Following its lead, some koulouri stands now look more and more like London or New York sandwich counters offering fillings galore.

Angelos Rentoulas, editor of the Gastronomos magazine, explains this new street food phenomenon.

"With the economic crisis, value for money is king; you want something substantial of good quality and taste," he says. "Street food was not always high level, but the low price contributed to its appeal and its return."

The recent influx of Middle Eastern migrants has also had an influence, he says.

"There was no falafel-eating culture in Greece for instance, but the Falafellas (Falafellas Aiolou 51, Athens; +30 210 3239 809) takeaway opened in the center of Athens and people went crazy."

Kioftes (or Keftes) is the Greek equivalent of falafel, an indigenous on-the-go street food and as such the main ingredient of Athenian picnic baskets.

Hidden away from the street by giant jasmine creepers, Kioftes has been a runaway success using "grandma's recipes from Smyrna dating from 1904" reminding many Greeks of their own migrations from the Middle East almost 100 years ago.

It has been so successful, it now aspires to be classed as full-blown restaurant offering appetizing Smyrniot dishes such as Meliassiá (bourek pastries with cheese honey and sesame), Aplotí (eggplants with cheese and tomato) and, of course, meatballs.

It's not all new. More traditional Greek street food has seen a recent resurgence.

Souvlaki (skewered grilled meat) has been reinvigorated and kebabs are back with a vengeance thanks to strict new quality controls that take the guesswork out of the ingredients.